“Life is like a box of LEGOs.” You can almost hear that catchphrase echoing across the decades as the preamble to Motorola’s surprise Project Ara: a smartphone you cobble together from pieces like a toy that’s not a toy.

It’s real — that’s a shot of some of the concept pieces laid out like an Ikea display above — and if it sounds familiar, say like something you read about last month, it’s because it is, and you did. You’re thinking of Phonebloks, the modular smartphone idea from Dutch designer Dave Hakkens. The Internet stumbled on it in September, a phone built out of swappable blocks with electricity-conducting connector pins, where each of the blocks was like a bullet point on a spec sheet: battery, processor, memory, storage, audio, wireless chip, gyroscope — you name it.

As I wrote at the time:

Want to slide in a faster processor? Just swap out a block. Cracked screen? Off with the old, on with the new. Don’t need the camera? Or maybe you do everything online and don’t need local storage? The freed up space might let you drop in a bigger battery or detach non-essential components you don’t want leeching electricity.

But it was all just concept stuff adrift in questions: What about particle and moisture ingress? Thermal dissipation? General ergonomics (to handle or hold)? Cost?

Motorola says it was already working on what it’s calling Project Ara when it bumped into Hakkens, at which point something like a mutual high-five occurred, with the two agreeing to buddy up — Motorola bringing the “deep technical work,” Hakkens bringing the community (when I wrote about Phonebloks last month, Hakkens’ YouTube explainer had a respectable four million views — as of today, that figure’s soared to over 16 million).

Project Ara is designed to be a “free, open hardware platform for creating highly modular smartphones,” says Motorola. Take note of that — a platform, not a specific model. Project Ara isn’t a single phone coming to a Motorola reseller near you, it’s Motorola pouring the foundation for a slew of new phones, including — hypothetically, anyway — some that could live outside of Motorola’s walled garden.

“We want to do for hardware what the Android platform has done for software,” writes Motorola, adding that it’s goal is “to give you the power to decide what your phone does, how it looks, where and what it’s made of, how much it costs, and how long you’ll keep it.”

Motorola

The concept’s not so different from Phonebloks: a durable endoskeleton (gunning for a catch-word, Motorola shortens this to “endo”) into which you place modules. “A module can be anything, from a new application processor to a new display or keyboard, an extra battery, a pulse oximeter–or something not yet thought of!”

What’s next? Motorola puts its nose to the grindstone, of course, but the company says it’ll engage with the Phonebloks community, presumably to solicit feedback, as well as send out invites to developers to start building modules for the platform. Look for a Module Developer’s Kit (MDK) to go alpha “sometime this winter,” and Motorola promises to divulge more “in the next few months.”

I love the idea, just as I loved the idea when I bumped into Phonebloks last month. Who wouldn’t? Trading one thing for another to get a little more of this or waste a little less of that? Discarding dated components for new ones without throwing everything away (and again, in theory, curbing a mushrooming waste stream)?

But it’s still just an idea. Even those sexy screenshots above tell us little about the device’s real-world tenability. Every last micrometer of an iOS or Android devices is fastidiously hyped-designed. There’s a reason every part and piece goes where it does, that every last sliver of free space is accounted for. Divvying these systems up into orthogonal modules — and the modules look definitively orthogonal — is going to sacrifice a certain amount of space per module. That space adds up. And what about assembly restrictions, say not placing one high-thermal part next to another? What about insulating the connector points from dust or water? And once everything’s glommed together, will it feel as rigid and durable as something made out of aluminum and glass?

We’ll see. I’m interested. I assume you’re interested. That’s all a company like Motorola needs to chip away at Project Ara until it gets it right.